PDSCH Reception Timing for Low-Capability Devices
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Solution Overview
Problem
In LTE-based communication systems, Machine-Type Communication (MTC) devices face challenges in receiving physical downlink shared channels (PDSCH) due to repeated transmissions of PDCCH and PUSCH, leading to difficulties in determining the correct reception timing of PDSCH, especially in coverage enhancement areas where PDCCH and PDSCH are repeatedly transmitted across multiple subframes.
Innovation Solution
A method where the wireless device drops PDSCH reception on invalid subframes and receives a System Information Block (SIB) to determine valid downlink subframes, allowing for synchronized reception of PDSCH and PUSCH bundles after receiving a bundle of M-PDCCHs, with timing adjustments based on predetermined gaps or signaled values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PDCCH and PDSCH are repeatedly transmitted according to coverage enhancement, then coverage reliability is improved, but device memory requirements and complexity increase
Solution Approach 1:
The patent applies preliminary action by defining a predetermined timing relationship between PDCCH and PDSCH before transmission occurs. The network configures the PDSCH reception timing offset (k0) in advance through RRC signaling, allowing the terminal to know exactly when to receive PDSCH without needing to store multiple PDCCH repetitions. This resolves the contradiction by maintaining coverage enhancement reliability while eliminating the need for increased device memory.
2Reliability
If PDCCH is repeatedly transmitted across multiple subframes for coverage enhancement, then downlink coverage is improved, but uplink timing determination becomes uncertain
Solution Approach 1:
The patent implements feedback by establishing a deterministic timing relationship where PDSCH reception timing is explicitly defined relative to PDCCH reception. The terminal uses the configured offset k0 to calculate PDSCH timing, and this timing information feeds back into determining PUSCH transmission timing. This resolves the timing uncertainty by creating a closed-loop timing determination mechanism that works reliably even with repeated PDCCH transmissions.
3Reliability
If the terminal stores all PDSCH transmissions until successful PDCCH decoding, then data reception reliability is improved, but processing delay and complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-configuring the timing relationship between PDCCH and PDSCH through RRC signaling before actual data transmission. The terminal receives the PDSCH reception timing offset (k0) in advance, allowing it to directly receive PDSCH at the predetermined time without storing previous transmissions. This eliminates processing delay while maintaining reliability through the pre-established timing relationship.
Data Source
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AI summary
The disclosure of the present specification provides a method for receiving a physical downlink shared channel (PDSCH) on a low-capability (LC) or low-cost (LC) device. The method may comprise the steps of: receiving repetition of a downlink control channel in the case that the LC device is set to coverage enhancement (CE); determining a last subframe where the reception is terminated; and determining a start subframe for receiving the repetition of the PDSCH on the basis of the last subframe. The reception of the PDSCH starts at the k-th effective subframe after subframe n, and the subframe n may be the last subframe where the reception of the downlink control channel is terminated. K is greater than or equal to 2, and the effective subframe may be predetermined.